Collection of adipose tissue through the application of liposuction methods is a common practice (Condé-Green, 2009). The procedure is easily performed in most cases, has a low morbidity rate, and results in the collection of large volumes of adipose tissue (Katz and Maiwald, 2005). Zuk, et al. (2001) was one of the first groups to demonstrate the presence of “stem” cells in adipose tissue collected via lipoaspiration. Their results have been confirmed in subsequent publications (e.g., Yoshimura, et al., 2006). Due to the presence of regenerative cells in the fat tissue, there has been growing interest in using tissue collected during liposuction for body contouring, facial/body enhancement and recontouring in patients suffering from soft tissue atrophy (Condé-Green, 2009). There also has been a growing interest in using the cells isolated from fat tissue for regenerative cell therapy in a variety of pathologies, including repair of orthopedic tissue injuries (Tapp, et al., 2009).
A number of publications demonstrate how lipoaspirates may be non-enzymatically processed to extract adipose-derived stem cells (ASCs) and progenitor cells from adipose tissue. It is apparent that viable cells can be obtained from mechanical dissociation of the fatty portion of lipoaspirate when collected following either centrifugation or washing of the fatty tissue, but non-enzymatic processing yields fewer cells per mL of lipoaspirate (Baptista, et al., 2009; Yoshimura, et al., 2006).
Collagenase digestion of the adipose tissue is the most common practice for enzymatically digesting lipoaspirates. Enzymatic processing of adipose tissue may yield a higher number of cells than current non-enzymatic processing methods; however, enzymatic processing results in more difficult processing, slower return of cells to the patient, higher cost to provide the cells, and more stringent FDA regulation. Many processing methods, both non-enzymatic and enzymatic, also ignore the fact that a significant amount of progenitor cells can be obtained from the lipoaspirate fluid alone with minimal processing.